Urban-rural factors affecting cancer mortality in Kentucky, 1950-1969.

Urban-rural factors associated with cancer mortality were studied in Kentucky to develop likely hypotheses on cancer prevention. Factor analysis was performed on county data for 25 variables which selected 17 variables for use in a multiple regression analysis. Age-adjusted cancer mortality rates used as outcome variables in this analysis included total and colorectal cancer (male, female, and both sexes combined) and female breast cancer. Each of these cancer sites was regressed against the 17 independent variables. Best predictive models for cancer outcome were selected on the basis of maximum total variance explained. Subsistence farming, where most of the farm produce is kept for home use rather than sold, was the single best predictor of low overall cancer rates for males, females, and both sexes combined in rural and Appalachian Kentucky. The subsistence farming diet is one based largely on milk and whole grains, rich in the following suspected anticarcinogens: selenium, magnesium, calcium, protease inhibitors, fiber, phenolics, and allelopaths. The diet lacks variety in fruits and vegetables and is low in vitamins A and C.